The Golgi apparatus is responsible for post-translational processing of the proteins and lipids biosynthesized in the ER, and then delivering them to different locations within and outside the cell. Considering the importance of the Golgi in protein traffic, its accurate duplication and inheritance during cell division are carefully orchestrated. In mammalian cells the Golgi exists in a higher order structure that is known as the Golgi ribbon, making direct observation of the duplication event difficult. Simpler eukaryotes that contain one or just a few Golgi stacks have therefore been used recently as model systems to study this process. Recent work in the Warren lab using the parasite Trypanosoma brucei has provided evidence that the old Golgi provides components necessary for establishing the new organelle, suggesting that its duplication is a templated process. T. brucei will be used to determine the precise contributions of the old Golgi and the new ER exit site to the construction of a new, functional Golgi. The carriers responsible for transport between the two Golgi and the role of other organelles in positioning the new Golgi will also be investigated. Specific Aims: (1) To determine if Golgi matrix proteins are transferred to the new Golgi prior to a glycosyltransferase; (2) to identify the carriers that mediate transfer from the old Golgi to the new; (3) to identify the role of the basal body in the inheritance of the new Golgi; (4) to observe when the new Golgi becomes competent to process cargo: (5) and to determine the role of the 'extra' Golgi that form during the late cell cycle.